Hong Suk-hui was waiting on the shore of South Korea's Jeju Island when the call came. His fishing boat had capsized.

Just two days earlier, the vessel had ventured out on what he had hoped would be a long and fruitful voyage. But as the winds grew stronger, its captain was ordered to turn back. On the way to port, a powerful wave struck from two directions creating a whirlpool, and the boat flipped. Five of the 10 crew members, who had been asleep in their cabins below deck, drowned.

"When I heard the news, I felt like the sky was falling," said Mr Hong.

Last year, 164 people were killed or went missing in accidents in the seas around South Korea – a 75% jump from the year before. Most were fishermen whose boats sunk or capsized.

"The weather has changed, it's getting windier every year," said Mr Hong, who also chairs the Jeju Fishing Boat Owners Association.

"Whirlwinds pop up suddenly. We fisherman are convinced it is down to climate change."

Alarmed by the spike in deaths, the South Korean government launched an investigation into the accidents.

This year, the head of the taskforce pinpointed climate change as one of the major causes, as well as highlighting other problems - the country's aging fishing workforce, a growing reliance on migrant workers, and poor safety training.

The seas around Korea are warming more rapidly than the global average, in part because they tend to be shallower. Between 1968 and 2024, the average surface temperature of the country's seas increased by 1.58C, more than double the global rise of 0.74C.

Warming waters are contributing to extreme weather at sea, creating the conditions for tropical storms, like typhoons, to become more intense.

They are also causing some fish species around South Korea to migrate, according to the country's National Institute of Fisheries Science, forcing fisherman to travel further and take greater risks to catch enough to make a living.

Environmental campaigners say urgent action is needed to "stop the tragedy occurring in Korean waters".

On a rainy June morning, Jeju Island's main harbour was crammed with fishing boats. The crews hurried back and forth between sea and land, refuelling and stocking up for their next voyage, while the boats' owners paced anxiously along the dock watching the final preparations.

"I'm always afraid something might happen to the boat, the risks have increased so much," said 54-year-old owner, Kim Seung-hwan. "The winds........

© BBC